A shrink tunnel is a device for supplying heated air to an enclosed chamber for the purpose of shrinking a polymeric film around a package for physical protection and enhanced appearance. Shrink tunnels in commercial use today generally include a mechanical conveyer for carrying packages through the chamber.
One weakness of prior art shrink wrap methods is that conveyor belts are generally made of a metal mesh or silicone rollers that become so hot that some heat sensitive packages are marred or destroyed. Also, the weight of the product package pressing against the shrink film will prevent the shrink film from shrinking evenly around the package. The portion of the product lying on the conveyor will hold the shrink film and its weight will prevent the film from shrinking as quickly and uniformly as in areas not affected by the conveyor.
Another disadvantage of existing shrink wrap tunnels is that they are built to handle a large variety of product sizes. Therefore, when running small packages the tunnel is operating with a large volume of unneeded hot air. This represents wasted energy.
A principal objective of the present invention is to provide a shrink tunnel assembly that avoids damaging or marring the appearance of film covered packages.
A related objective of the invention is to provide a shrink tunnel assembly that operates more efficiently by reducing the volume of wasted hot air. This reduces energy costs for the tunnel operation, associated costs for conditioning the operating environment and, in an embodiment having no moving parts, reduces noise pollution and maintenance.
Additional objectives and advantages of my invention will become apparent to persons skilled in the art from the following detailed description of a preferred embodiment.